The preparation of .alpha.-aminonitriles, which are recognized, for example, as intermediates for the synthesis of .alpha.-amino acids and nitrogen-containing heterocycles which are biologically important compounds, can be undertaken by reacting a carbonyl compound, such as an aldehyde or a ketone, for example, with amines and a cyanide source. One cyanide source which can be used is hydrogen cyanide. If hydrogen cyanide is not selected as the cyanide source, the carbonyl compound needs to be first reacted with one equivalent of bisulfite, such as sodium bisulfite, prior to adding the amine and cyanide source, such as alkali metal cyanide, to avoid imine formation. The amount of imine formation is also dependent upon the carbonyl compound used with, for example, a longer chain aldehyde, such as 2-ethylhexanal, yielding more imine formation than a shorter chain aldehyde, such as isobutyraldehyde. The reaction of a bisulfite adduct of the selected carbonyl compound, amine, and alkali metal cyanide in aqueous solution is the well-known Knoevenagel-Bucherer method (see Russian Chemical Reviews 58(2), 148-162 (1989); Chemical Reviews 42: 189 and following, at 238 (1942); and The Chemistry of the Cyano Group, Z. Rappoport, ed., p. 75 (1970).
Certain prior art references provide details of such synthetic procedures in which the desired .alpha.-aminonitrile is formed as an organic phase which separates from the aqueous layer which contains aqueous alkali metal sulfite. For example, in U.S. Pat. No. 2,164,781 the .alpha.-aminonitrile product in the Oil is indicated as being saponified in the reaction mixture by the addition of caustic. Hauser et al. in Journal of the American Chemical Society, Vol. 82, 1786-1789 (1960) indicates in its experimental section that the aqueous layer is extracted with ether, the ether extract is combined with the original organic layer, and the combination is dried. Presumably, the aqueous layer was discarded. Luten, Jr. et al., in Journal of Organic Chemistry, Vol. 3, 588-597 (1938-39) the .alpha.-aminonitrile layer is merely separated from the aqueous layer, is dried, and is vacuum distilled. Again, the aqueous layer is presumably discarded.